This is one of the hardest eating disorders to beat. If you have only newly begun purging, please consider stopping immediately.
And yes, the fact that you feel "good" after purging is because the reward system in your brain is whack. It perceives purging and restriction as a reward, and treatment can help you reprogram (citation below).
Citation: Decoding Anorexia: How Breakthroughs in Science Offer Hope for Eating Disorders https://www.amazon.com/dp/0415898676/ref=cm_sw_r_awdo_navT_g_CNSGJJ8PPBGPF0FKXEZD
This is a good book
Decoding Anorexia: How Breakthroughs in Science Offer Hope for Eating Disorders https://www.amazon.co.uk/dp/0415898676/ref=cm_sw_r_cp_api_glt_fabc_2WTHG31EPWV1KXDV4FKY